[PATCH v2 06/14] drm/edid: parse YCBCR420 videomodes from EDID
Ville Syrjälä
ville.syrjala at linux.intel.com
Thu Jul 13 16:21:18 UTC 2017
On Thu, Jul 13, 2017 at 09:03:12PM +0530, Shashank Sharma wrote:
> HDMI 2.0 spec adds support for YCBCR420 sub-sampled output.
> CEA-861-F adds two new blocks in EDID's CEA extension blocks,
> to provide information about sink's YCBCR420 output capabilities.
>
> These blocks are:
>
> - YCBCR420vdb(YCBCR 420 video data block):
> This block contains VICs of video modes, which can be sopported only
> in YCBCR420 output mode (Not in RGB/YCBCR444/422. Its like a normal
> SVD block, valid for YCBCR420 modes only.
>
> - YCBCR420cmdb(YCBCR 420 capability map data block):
> This block gives information about video modes which can support
> YCBCR420 output mode also (along with RGB,YCBCR444/422 etc) This
> block contains a bitmap index of normal svd videomodes, which can
> support YCBCR420 output too.
> So if bit 0 from first vcb byte is set, first video mode in the svd
> list can support YCBCR420 output too. Bit 1 means second video mode
> from svd list can support YCBCR420 output too, and so on.
>
> This patch adds two bitmaps in display's hdmi_info structure, one each
> for VCB and VDB modes. If the source is HDMI 2.0 capable, this patch
> adds:
> - VDB modes (YCBCR 420 only modes) in connector's mode list, also makes
> an entry in the vdb_bitmap per vic.
> - VCB modes (YCBCR 420 also modes) only entry in the vcb_bitmap.
>
> Cc: Ville Syrjala <ville.syrjala at linux.intel.com>
> Cc: Jose Abreu <joabreu at synopsys.com>
> Cc: Emil Velikov <emil.l.velikov at gmail.com>
>
> V2: Addressed
> Review comments from Emil:
> - Use 1ULL<<i instead of 1<<i to make sure the output is 64bit.
> - Use the suggested method for updating dbmap.
> - Add documentation for YCBCR420_vcb_map to fix kbuild warning.
>
> Review comments from Ville:
> - Do not expose the YCBCR420 flags in uabi layer, keep it internal.
> - Save a map of YCBCR420 modes for future reference.
> - Check db length before trying to parse extended tag.
> - Add a warning if there are > 64 modes in capability map block.
> - Use y420cmdb in function names and macros while dealing with vcb
> to be aligned with spec.
> - Move the display information parsing block ahead of mode parsing
> blocks.
>
> V3: Addressed design/review comments from Ville
> - Do not add flags in video modes, else we have to expose them to user
> - There should not be a UABI change, and kernel should detect the
> choice of the output based on type of mode, and the bitmaps.
> - Use standard bitops from kernel bitmap header, instead of calculating
> bit positions manually.
>
> V4: Addressed review comments from Ville:
> - s/ycbcr_420_vdb/y420vdb
> - s/ycbcr_420_vcb/y420cmdb
> - Be less verbose on description of do_y420vdb_modes
> - Move newmode variable in the loop scope.
> - Use svd_to_vic() to get a VIC, instead of 0x7f
> - Remove bitmap description for CMDB modes & VDB modes
> - Dont add connector->ycbcr_420_allowed check for cmdb modes
> - Remove 'len' variable, in is_y420cmdb function, which is used
> only once
> - Add length check in is_y420vdb function
> - Remove unnecessary if (!db) check in function parse_y420cmdb_bitmap
> - Do not add print about YCBCR 420 modes
> - Fix indentation in few places
> - Move ycbcr420_dc_modes in next patch, where its used
> - Add a separate patch for movement of drm_add_display_info()
>
> V5: Addressed review comments from Ville:
> - Add the patch which cleans up the current EXTENDED_TAG usage
> - Make y420_cmdb_map u64
> - Do not block ycbcr420 modes while parsing the EDID, rather
> add a separate helper function to prune ycbcr420-only modes from
> connector's probed modes.
>
> V6: Rebase
> V7: Move this patch after the 420_only validation patch (Ville)
>
> Signed-off-by: Shashank Sharma <shashank.sharma at intel.com>
> ---
> drivers/gpu/drm/drm_edid.c | 148 +++++++++++++++++++++++++++++++++++++++++++-
> include/drm/drm_connector.h | 12 ++++
> 2 files changed, 158 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 96eee5a..b86afb9 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -2783,6 +2783,8 @@ add_detailed_modes(struct drm_connector *connector, struct edid *edid,
> #define SPEAKER_BLOCK 0x04
> #define USE_EXTENDED_TAG 0x07
> #define EXT_VIDEO_CAPABILITY_BLOCK 0x00
> +#define EXT_VIDEO_DATA_BLOCK_420 0x0E
> +#define EXT_VIDEO_CAP_BLOCK_Y420CMDB 0x0F
> #define EDID_BASIC_AUDIO (1 << 6)
> #define EDID_CEA_YCRCB444 (1 << 5)
> #define EDID_CEA_YCRCB422 (1 << 4)
> @@ -3155,15 +3157,79 @@ drm_display_mode_from_vic_index(struct drm_connector *connector,
> return newmode;
> }
>
> +/*
> + * do_y420vdb_modes - Parse YCBCR 420 only modes
> + * @connector: connector corresponding to the HDMI sink
> + * @svds: start of the data block of CEA YCBCR 420 VDB
> + * @len: length of the CEA YCBCR 420 VDB
> + *
> + * Parse the CEA-861-F YCBCR 420 Video Data Block (Y420VDB)
> + * which contains modes which can be supported in YCBCR 420
> + * output format only.
> + */
> +static int do_y420vdb_modes(struct drm_connector *connector,
> + const u8 *svds, u8 svds_len)
> +{
> + int modes = 0, i;
> + struct drm_device *dev = connector->dev;
> + struct drm_display_info *info = &connector->display_info;
> + struct drm_hdmi_info *hdmi = &info->hdmi;
> +
> + for (i = 0; i < svds_len; i++) {
> + u8 vic = svd_to_vic(svds[i]);
> + struct drm_display_mode *newmode;
> +
Hmm. Looks like here we will need the drm_valid_cea_vic() check
because the vic is coming from an untrusted source.
> + newmode = drm_mode_duplicate(dev, &edid_cea_modes[vic]);
> + if (!newmode)
> + break;
> + bitmap_set(hdmi->y420_vdb_modes, vic, 1);
> + drm_mode_probed_add(connector, newmode);
> + modes++;
> + }
> +
> + if (modes > 0)
> + info->color_formats |= DRM_COLOR_FORMAT_YCRCB420;
> + return modes;
> +}
> +
> +/*
> + * drm_add_cmdb_modes - Add a YCBCR 420 mode into bitmap
> + * @connector: connector corresponding to the HDMI sink
> + * @vic: CEA vic for the video mode to be added in the map
> + *
> + * Makes an entry for a videomode in the YCBCR 420 bitmap
> + */
> +static void
> +drm_add_cmdb_modes(struct drm_connector *connector, u8 svd)
> +{
> + u8 vic = svd_to_vic(svd);
> + struct drm_hdmi_info *hdmi = &connector->display_info.hdmi;
And maybe here. It's not actually needed since we know it's valid
because drm_display_mode_from_vic_index() returned a mode, but since
that's not immediately obvious from here we might want to have the
check. But if you disagree feel free to leave it out.
At some point I think we might want to reorganize
drm_display_mode_from_vic_index() such that we actually pass it the
vic instead. Then we could also pass the vic here directly.
> +
> + bitmap_set(hdmi->y420_cmdb_modes, vic, 1);
> +}
> +
> static int
> do_cea_modes(struct drm_connector *connector, const u8 *db, u8 len)
> {
> int i, modes = 0;
> + struct drm_hdmi_info *hdmi = &connector->display_info.hdmi;
>
> for (i = 0; i < len; i++) {
> struct drm_display_mode *mode;
> mode = drm_display_mode_from_vic_index(connector, db, len, i);
> if (mode) {
> + /*
> + * YCBCR420 capability block contains a bitmap which
> + * gives the index of CEA modes from CEA VDB, which
> + * can support YCBCR 420 sampling output also (apart
> + * from RGB/YCBCR444 etc).
> + * For example, if the bit 0 in bitmap is set,
> + * first mode in VDB can support YCBCR420 output too.
> + * Add YCBCR420 modes only if sink is HDMI 2.0 capable.
> + */
> + if (hdmi->y420_cmdb_map & (1 << i))
I think this needs to be something like
if (i < 64 && hdmi->y420_cmdb_map & (1ULL << i))
With those changes I think this part should be good to go.
> + drm_add_cmdb_modes(connector, db[i]);
> +
> drm_mode_probed_add(connector, mode);
> modes++;
> }
> @@ -3505,9 +3571,78 @@ static bool cea_db_is_hdmi_forum_vsdb(const u8 *db)
> return oui == HDMI_FORUM_IEEE_OUI;
> }
>
> +static bool cea_db_is_y420cmdb(const u8 *db)
> +{
> +
> + if (cea_db_tag(db) != USE_EXTENDED_TAG)
> + return false;
> +
> + if (!cea_db_payload_len(db))
> + return false;
> +
> + if (cea_db_extended_tag(db) != EXT_VIDEO_CAP_BLOCK_Y420CMDB)
> + return false;
> +
> + return true;
> +}
> +
> +static bool cea_db_is_y420vdb(const u8 *db)
> +{
> + if (cea_db_tag(db) != USE_EXTENDED_TAG)
> + return false;
> +
> + if (!cea_db_payload_len(db))
> + return false;
> +
> + if (cea_db_extended_tag(db) != EXT_VIDEO_DATA_BLOCK_420)
> + return false;
> +
> + return true;
> +}
> +
> #define for_each_cea_db(cea, i, start, end) \
> for ((i) = (start); (i) < (end) && (i) + cea_db_payload_len(&(cea)[(i)]) < (end); (i) += cea_db_payload_len(&(cea)[(i)]) + 1)
>
> +static void drm_parse_y420cmdb_bitmap(struct drm_connector *connector,
> + const u8 *db)
> +{
> + struct drm_display_info *info = &connector->display_info;
> + struct drm_hdmi_info *hdmi = &info->hdmi;
> + u8 map_len = cea_db_payload_len(db) - 1;
> + u8 count;
> + u64 map = 0;
> +
> + if (map_len == 0) {
> + /* All CEA modes support ycbcr420 sampling also.*/
> + hdmi->y420_cmdb_map = U64_MAX;
> + info->color_formats |= DRM_COLOR_FORMAT_YCRCB420;
> + return;
> + }
> +
> + /*
> + * This map indicates which of the existing CEA block modes
> + * from VDB can support YCBCR420 output too. So if bit=0 is
> + * set, first mode from VDB can support YCBCR420 output too.
> + * We will parse and keep this map, before parsing VDB itself
> + * to avoid going through the same block again and again.
> + *
> + * Spec is not clear about max possible size of this block.
> + * Clamping max bitmap block size at 8 bytes. Every byte can
> + * address 8 CEA modes, in this way this map can address
> + * 8*8 = first 64 SVDs.
> + */
> + if (WARN_ON_ONCE(map_len > 8))
> + map_len = 8;
> +
> + for (count = 0; count < map_len; count++)
> + map |= (u64)db[2 + count] << (8 * count);
> +
> + if (map)
> + info->color_formats |= DRM_COLOR_FORMAT_YCRCB420;
> +
> + hdmi->y420_cmdb_map = map;
> +}
> +
> static int
> add_cea_modes(struct drm_connector *connector, struct edid *edid)
> {
> @@ -3530,10 +3665,16 @@ add_cea_modes(struct drm_connector *connector, struct edid *edid)
> video = db + 1;
> video_len = dbl;
> modes += do_cea_modes(connector, video, dbl);
> - }
> - else if (cea_db_is_hdmi_vsdb(db)) {
> + } else if (cea_db_is_hdmi_vsdb(db)) {
> hdmi = db;
> hdmi_len = dbl;
> + } else if (cea_db_is_y420vdb(db)) {
> + const u8 *vdb420 = &db[2];
> +
> + /* Add 4:2:0(only) modes present in EDID */
> + modes += do_y420vdb_modes(connector,
> + vdb420,
> + dbl - 1);
> }
> }
> }
> @@ -4216,6 +4357,8 @@ static void drm_parse_cea_ext(struct drm_connector *connector,
> drm_parse_hdmi_vsdb_video(connector, db);
> if (cea_db_is_hdmi_forum_vsdb(db))
> drm_parse_hdmi_forum_vsdb(connector, db);
> + if (cea_db_is_y420cmdb(db))
> + drm_parse_y420cmdb_bitmap(connector, db);
> }
> }
>
> @@ -4477,6 +4620,7 @@ int drm_add_edid_modes(struct drm_connector *connector, struct edid *edid)
> num_modes += add_cea_modes(connector, edid);
> num_modes += add_alternate_cea_modes(connector, edid);
> num_modes += add_displayid_detailed_modes(connector, edid);
> +
> if (edid->features & DRM_EDID_FEATURE_DEFAULT_GTF)
> num_modes += add_inferred_modes(connector, edid);
>
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index 26dd3eb..225e092 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -143,6 +143,17 @@ struct drm_hdmi_info {
> * upto 128 VICs;
> */
> unsigned long y420_vdb_modes[BITS_TO_LONGS(128)];
> +
> + /**
> + * @y420_cmdb_modes: bitmap of modes which can support ycbcr420
> + * output also, along with normal HDMI outputs. There are total 107
> + * VICs defined by CEA-861-F spec, so the size is 128 bits to map upto
> + * 128 VICs;
> + */
> + unsigned long y420_cmdb_modes[BITS_TO_LONGS(128)];
> +
> + /** @y420_cmdb_map: bitmap of SVD index, to extraxt vcb modes */
> + u64 y420_cmdb_map;
> };
>
> /**
> @@ -206,6 +217,7 @@ struct drm_display_info {
> #define DRM_COLOR_FORMAT_RGB444 (1<<0)
> #define DRM_COLOR_FORMAT_YCRCB444 (1<<1)
> #define DRM_COLOR_FORMAT_YCRCB422 (1<<2)
> +#define DRM_COLOR_FORMAT_YCRCB420 (1<<3)
>
> /**
> * @color_formats: HDMI Color formats, selects between RGB and YCrCb
> --
> 2.7.4
--
Ville Syrjälä
Intel OTC
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